It is known that in some disorders of the knee, and in particular during post-operative rehabilitation therapy following surgery involving the ligaments or other parts of the knee joint, it is necessary to use special knee braces or walkers that provide a certain degree of support to the still weak joint, absorbing the most intense stress.
Various types of knee braces are currently known and available, but in the majority of cases these consist of a rigid articulated frame, with a covering, padding and means for fixing to the leg.
All the components that make up the knee brace are constructed in such a way as to envelop the knee in order to ensure adequate support during walking, or in any case to guarantee the support of an impaired articulation.
The frames of traditional knee braces, rigid and articulated as stated above, comprise lateral uprights that are restrained by means of appropriate connections to the femoral and the tibial parts of the leg, and a connecting structure between these uprights consisting of a hinged joint at the level of the knee.
According to the most recent and advanced solutions, each of these hinged joints comprises pairs of pins that make up the same number of points of application and joints for the ends of the femoral and tibial uprights, in order to obtain a sufficiently mobile structure that allows sufficient articulation of the knee and at the same time a good level of stress resistance.
The known knee braces and walkers are normally equipped with straps or half-rings that permit the brace to be fixed close to the knee joint and blocked in the femoral and tibial areas.
The known articulated joints, which consist of pairs of pivots theoretically pre-arranged to allow correct movement of the limb, perform a certain extension outwards during flexion of the knee, while they tend to contract during extension of the knee, thus reducing the possibility of the knee brace moving and in particular of it slipping down.
There are also known articulated knee brace joints that are equipped with means that allow alteration of the configuration, in order to satisfy different requirements according to the size of the knee and to the type of mobility to be applied in the various cases and types of injuries or traumatic events.
The U.S. Pat. No. 6,551,264 in the name of Berg, Inc. foresees a knee brace equipped with a retaining sector that can be applied on the patella area.
According to this solution the rack end (156, 158) of the uprights (12, 14) positioned on the two hinges (156, 158) is connected to the double comb toothing (166) of a mobile bracket (162) that supports tension straps (78, 80), inserted in appropriate slots (110, 112) and designed to envelop the knee close to the patella.
The aim of this system is to fix the brace not only to the femoral and tibial areas but also to the patella area in order to accompany the movements of the brace during the flexion of the knee and to reduce the possibility of the brace moving from its position, preventing it in particular from slipping down.
It can nevertheless be noted that according to this solution the bracket (162) is positioned and moves in a substantially symmetrical and specular way with respect to the hypothetical median axis of the joint lying on the straight line equidistant between the two pins (152, 154) of the two uprights (12, 14).
This means a substantial limitation relative to the fact that from the anatomical point of view the patella does not move in a symmetrical and specular way with respect to the bisecting line of the knee joint, but slides in a misaligned way in its anatomical trochlear site.
It is in fact known that the knee is an extremely complex joint, subjected to forces that are exerted simultaneously on several planes, imposing considerable and diversified stress on the bone, capsular, meniscal, ligamentous and myotendinous structures.
In particular, the angular movement of the femoral-patella articulation of the knee is not exactly symmetrical and specular with respect to the hypothetical axis of symmetry between the femur and the tibia, but is more pronounced near the femoral part, which extends more during flexion.
The patella also slides in its site or trochlea during the bending of the joint, moving in its natural sliding plane, which is formed by the femoral groove, in a more pronounced way in the femoral part.
The disadvantage which has therefore been a common finding in all types of walkers and knee braces proposed to date on the market, and referring in particular to those equipped with bracket means that support the tension straps designed to envelop the knee close to the patella, is relative to the fact that the movement of the patella is not respected with this type of bracket.
In reality this drawback is due to the fact that the movement of the patella is not symmetrical with respect to the axis of symmetry between the femur and the tibia, and the known solutions do not foresee means that allow patellar brackets to follow the diversified movement of the patella that takes place between the tibial part and the femoral part.
This means that, even in the presence of bracket means designed to intervene in the patellar area to limit the possibility of the knee brace moving, a certain degree of slipping of the brace does take place, mainly downwards, since the symmetrical movement of the patellar bracket with respect to its sliding area does not correspond to the asymmetrical movement of the patella.